In 2016, Hutchinson contracted Barr Engineering Co. to help with a study of the Hutchinson river and lake basin. The study included Campbell and Otter lakes, which make up about 650 acres of connected water created by the dam adjacent to the Main Street bridge.
The total cost of the study was about $25,000. What the city got in return was the most thorough examination ever of its river basin and dam. It also included recommendations for improvements.
The city’s environmental specialist, John Paulson, presented findings from the study’s final report during a public meeting this past Tuesday. Here’s what you need to know.
It’s the first study of its kind.
Hutchinson’s river basin is one of the town’s greatest resources. Generations of Hutchinson residents have gone to it for recreation, but not much was known about it, at least from a scientific point of view.
“We didn’t have a lake map of the basin since 1976,” Paulson said. “So it was more to just pull the barometer out and see where we’re at today. That was the biggest piece of it. And if we’re going to do that, let’s look at more than just depth.”
Paulson said the information will also be valuable as guidance for future decisions.
“I think it was well overdue, and I think it should serve us well moving forward, as far as something we can continue to refer back to,” he said.
They looked at everything.
Along with surveying the dam, a bathymetric survey — a fancy term for underwater depth — was conducted using sonar equipment. That info was compared to a 1976 study from the Minnesota Department of Natural Resources. Areas with significant floating vegetation were also documented and identified with help from the DNR.
Finally, sediment samples were collected for evaluating the thickness of soft sediment, characteristics including the presence of other materials, and the baseline analytical chemistry. Samples were also analyzed for Minnesota Pollution Control Agency-recommended readings of toxins such as arsenic, lead, nitrate and more.
The spillway is good.
The current rock spillway, which was reconstructed in 2008 to provide a passive structure for fish and other aquatic species to go through, is in fine condition and functioning as designed. The boulders are staying put and no changes were recommended.
It’s getting shallower.
According to the 2016-17 bathymetry study, Campbell Lake is up to 2 feet shallower overall compared to the 1976 data. Otter Lake south of the Crow River discharge remains the deepest and most consistent area, running up to 6 feet deep in some areas. But it was a couple feet shallower in areas such as the south shoreline west of School Road bridge, the north shoreline between Masonic Park and Jaycees Park, and from Jaycees Park to the dam. Lewis Bay also measured 4 feet shallower.
What just touched my leg?!
If you don’t like swimming through beds of underwater weeds, there’s bad news. They’re getting worse.
During the drawdown of the basin for the 2008 dam project, there were only a few, isolated areas with aquatic vegetation. Today, curly-leaf pondweed is growing more widespread, especially in areas shallower than 3 feet. This particular weed spreads quickly and can cause problems with dense beds of the plant that make swimming and boating difficult.
Eradicating them entirely is not realistic, but there are chemical and mechanical solutions to control the spread, the report said.
Water quality is questionable.
Analysis of sediment samples did not detect toxins at concerning levels, and as for its makeup, that checked out, too: organic silt, clay, leaves, twigs, shells, peat and other organic materials.
That’s good, however the water itself has its problems. Sedimentation and nutrient enrichment have given the water a poor, eutrophic quality, which essentially means more plants and less animals due to oxygen deprivation. The lakes are designated as “impaired water” by the MPCA, which means they are too polluted to meet water quality standards. This has had an effect on recreational use.
“Most people would think the clearer water is more pleasant to swim in. More appealing,” Paulsen said.
What happens next?
Nothing, Paulson said. Unless, of course, residents want to do something.
Dredging areas of the basin and making them deeper is likely the only option available to remove sediment, but that would only be temporary if nothing were done to control where the sediment is coming from. Along with the Crow River, there are 37 direct stormwater discharges that contribute to the sediment load. Investing in stormwater sediment control would be expensive and difficult to maintain, but without it the problem would likely keep returning.
If the city does look at dredging the lake, the priority list would start with West River Park boat landing, the Crow River delta and areas immediately east of it, the channels connecting Campbell and Otter lakes, and an area in Campbell Lake.
Ultimately, the study’s purpose was to gather the information and inform the public. Some may say the current state of the lakes is acceptable, while others may disagree. Where the conversation goes from here is up to the people.
“It’s just a fact-based approach and report of the status of the basin and the river itself,” he said. “Let people draw their own conclusions from it.”
